Electronics enclosures, such as cabinets, are utilized for storing, housing, and protecting various electronics, such as those utilized for wireless or cellular communications. For example, pressurized outdoor electronic cabinets are often utilized to house electronic modules, such as multi-carrier power amplifiers (MCPA's) that generate significant amounts of heat. For cooling the electronics, the cabinets, or other enclosures, are ventilated such that ambient air is drawn into the cabinet and through the interior space of the cabinet to circulate around the electronic components, before being exhausted to the outside of the cabinet. To that end, generally, such cabinets utilize one or more inlet or intake openings that are in communication with air intake devices, such as fans. When the fans are activated or ON, outside ambient air is drawn through the inlet openings into the interior space of the cabinet. Presumably, the interior space is at a higher temperature than the ambient air temperature due to the heat generated by the electronic components contained therein. The ambient air circulates, and cools the components, and, in the process, the circulating air is heated. The heated air is then exhausted through outlet openings or exit openings formed in the cabinet, generally on the side of the cabinet opposite to the inlet openings.
Such openings are usually formed by multiple slits or perforations in the cabinet walls. Screens, or air filters, might be utilized in conjunction with the openings. During use, the openings, or the air filters associated therewith, might become clogged, such as from particulate debris in the circulating air or from large obstructions, such a sheet of paper being drawn up against the inlet openings. With the blocked or restricted forced airflow through the pressurized electronic cabinet, the electronic modules, or components therein, such as amplifiers, may overheat. Oftentimes, such electronic modules are equipped with their own detector to detect overheating, and the modules will shut down to prevent damage to the electronics. However, as may be appreciated, such a shut down of the electronics results in the loss of service to the wireless customers, such as cell phone subscribers. Therefore, it is desirable to detect the condition of the airflow within the electronics cabinet and the conditions of the inlet and outlet openings, and overall performance of the ventilation system.
To that end, some existing methods detect a clogged condition by detecting the speed of the air that exits the filters at the outlet openings in the cabinet. A reduction in the air speed of the exiting air would indicate a clogged filter at the input. However, such air speed sensors only detect localized airflow, and, therefore, are susceptible to issuing false alarms. For example, clogging of the air filter in the immediate vicinity of a sensor can result in a local reduction in the airflow. However, the remainder of the filter might be unrestricted. Or other filters may be unclogged and operating properly. Thus, any alarm condition would be unnecessary.
In other systems, high temperature alarms, provided by sensors within a cabinet, may be used to signal a possible reduction in airflow through the cabinet. However, in practice, the alarm points for such high temperature alarms are often set so low that false alarms are issued. Alternatively, the alarm point might be set so high that the equipment shutdown can occur before an alarm is actually issued. Both such conditions are undesirable.
Furthermore, a temperature detector only detects the overheating of an electronics module. It does not provide any indication of the reason for such overheating. For example, if the ambient temperature around the cabinet is high, and the inlet openings and filters become clogged, a high temperature cabinet alarm may issue. There is no indication that restricted airflow through the cabinet is a problem, nor is there any indication provided of an impending module overheating.
In some cabinets, a fan failure alarm might be provided when a fan shuts down. However, such fan failure alarms are often logically OR'd with a high temperature cabinet alarm. Therefore, a high temperature condition might be falsely indicated in the cabinet if a fan fails while the ambient temperature is high.
Accordingly, it is desirable to maintain the ventilation within an electronics cabinet or enclosure to prevent the unnecessary shutdown of the modules therein. Furthermore, it is desirable to provide an operator with an indication of flow-through conditions in the ventilation system of a cabinet without undue false alarms. It is further desirable to rectify a clogged intake condition before issuing an alarm, and to still adequately cool the electronic components when a blocked condition exists.